Method and apparatus for the offshore installation of multi-ton packages such as deck packages and jackets

ABSTRACT

A method and apparatus for the installation or removal of large multi-ton prefabricated deck packages ( 16 ) includes the use of usually two barges ( 11, 12 ) defining a base ( 13, 14 ) that can support a large multi-ton load. A variable dimensional truss assembly is supported by the barge and forms a load transfer interface between the barge and the deck package. Each boom ( 21, 22 ) has a lifting end portion with a roller ( 63 ) that fits a receptacle ( 75 ) on the package. Tensile connections form attachments ( 130-134 ) between the deck package and barge at a lower elevational position. The variable dimension truss includes at least one member of variable length ( 130-134 ), in the preferred embodiment being a winch powered cable ( 130-134 ) that can be extended and retracted by winding and unwinding the winch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of U.S. patent application Ser. No. 08/915,617, filed Aug. 21, 1997, now U.S. Pat. No. 6,149,350; U.S. patent application Ser. No. 08/915,925, filed Aug. 21, 1997, now U.S. Pat. No. 5,975,807; U.S. patent application Ser. No. 08/925,929, filed Sep. 8, 1997, now U.S. Pat. No. 6,039,506; and U.S. patent application Ser. No. 08/709,014, filed Sep. 6, 1996, now U.S. Pat. No. 5,800,093, which is a continuation-in-part of copending U.S. Pat. application Ser. No.08/615,838, filed Mar. 14, 1996, now U.S. Pat. No. 5,662,434, which is a continuation-in-part of copending U.S. patent application Ser. No. 08/501,717, filed Jul. 12, 1995, now U.S. Pat. No. 5,607,260, which is a continuation-in-part of U.S. application Ser. No. 08/404,421 filed Mar. 15, 1995, now U.S. Pat. No. 5,609,441.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

REFERENCE TO A “MICROFICHE APPENDIX”

Not applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the placement of large multi-ton prefabricated deck packages (e.g. oil and gas platforms, oil rigs) in an offshore environment upon a usually partially submerged jacket that extends between the seabed and the water surface. Even more particularly, the present invention relates to the use of a moving lifting assembly which is preferably barge supported that can place a very large deck package upon an offshore marine jacket foundation without the use of enormous lifting booms such as form a part of derrick barges, offshore cranes, and the like, and wherein opposed short booms are connected with a frame or compressive spreader members that enable use of suspended slings to lift the deck package

2. General Background

In the offshore oil and gas industry, the search for oil and gas is often conducted in a marine environment. Sometimes the search takes place many miles offshore. Oil and gas well drilling takes place in many hundreds of feet of water depth.

The problem of drilling oil wells offshore and then producing these wells has been solved in part by the use of enormous fixed or floating platform structures with foundations that are mostly submerged, but usually extending a number of feet above the water surface. Upon this foundation (or “jacket”, tension leg platform (“TLP”), or SPAR, etc. as it is called in the art) there is usually placed a very large prefabricated rig or deck platform. The term “deck platform” as used herein should be understood to include any of a large variety of prefabricated structures that are placed on an offshore foundation to form a fixed or floating offshore platform. Thus, a “deck-platform” can include, e.g. a drilling rig, a production platform, a crew quarters, living quarters, or the like.

As an example of one offshore foundation, a supporting jacket is usually a very large multi-chord base formed of multiple sections of structural tubing or pipe that are welded together. Such jackets have been used for a number of years for the purpose of supporting large deck platforms in an offshore environment.

The jacket or foundation is usually prefabricated on land in a fabrication yard, preferably adjacent to a navigable waterway. The completed jacket can be placed upon a large transport barge so that it can be moved to the drill site where it will be placed upon the ocean floor. As an example, an offshore jacket can be several hundred feet in length. The size of the jacket is of course a function of the depth of water in which the rig will be placed. A five hundred (500) foot water depth at the drill site (or production site) will require a jacket which is approximately 500-550 feet tall. The jacket is usually partially submerged, with only a small upper portion of the jacket extending slightly above the water surface. An offshore jacket as described and in its position on the seabed can be seen, for example, in the Blight, et al U.S. Pat. No. 4,252,469 entitled “Method and Apparatus for installing integrated Deck Structure and Rapidly Separating Same from Supporting Barge Means.” Specifically, FIGS. 1, 2 and 3 of the Blight, et al patent show an offshore jacket on one seabed.

A small upper portion of the jacket extends above the water surface. This exposed portion of the jacket is the portion upon which the “deck platform” is placed and supported by. This upper portion of the jacket is usually equipped with a number of alignment devices which enhance the proper placement of the deck package on the jacket. Such alignment devices are referred to variously as stabbing eyes, sockets, or the like. The use of such alignment devices, sockets, or stabbing eyes can be seen in the Blight, et al U.S. Pat. Nos. 4,252,468 and 4,252,469 as well as in the Kansan U.S. Pat. No. 4,242,011. For purposes of background and reference, the Kansan U.S. Pat. No. 4,242,011 is incorporated herein by reference. The Blight, et al U.S. Pat. Nos. 4,252,469 and 4,252,468 are likewise each incorporated herein by reference.

Deck platforms or topsides can be extremely large and have correspondingly heavy weights. For example, it is not uncommon for a deck platform such as a drilling rig crew quarters, production platform or the like to be between five hundred and five thousand (500 and 5,000) tons gross weight. Topsides in excess of ten thousand (10,000) tons have been installed, and others that are being planned may weigh as much as thirty thousand (30,000) tons. Such enormous load values present significant problems in the placement of deck platforms on offshore jacket structures. First, the placement is done entirely in a marine environment. While the jacket can be laid on its side and/or floated into position, the platform is not a submersible structure, and must be generally supported in an upright condition above the water surface to prevent water damage to the many components that form a part of the drilling or production platform (such as electrical systems, wall constructions, and other portions that will be inhabited by individuals and used as oil and gas well drilling or production equipment).

The art has typically used enormous derrick barges for the purpose of setting or placing deck packages on jackets in an offshore environment. These derrick barges are large, rectangular barge structures with a high capacity lifting boom mounted at one end portion of the deck of the barge. The barge, for example might be three hundred to four hundred (300-400) feet in length, fifty to seventy five (50-75) feet in width, and twenty-five to fifty (25-50) feet deep. These figures are exemplary.

A derrick barge might have a lifting capacity of for example, two thousand (2,000) tons. For very large structures such as for example, a five thousand (5,000) ton deck package, two derrick barges can be used, each supporting one side portion of the deck platform with a multi-line lift system supported by an enormous structural boom extending high into the air above the package during the lift.

The boom simply works in the same way as an anchor lifting boom, namely the loadline raises and/or lowers the package into its proper position upon the jacket. While the use of such derrick barges has been very successful in the placing of offshore deck packages on jackets through the years, such derrick barges are generally limited in their capacity to packages of two thousand (2,000) tons or less. Further, derrick barges of such an enormous capacity are extremely expensive to manufacture and operate. Many thousand of dollars per hour as a cost of using such a device is not uncommon. Although there are five (5) or six (6) derrick barges that can lift in excess of six thousand (6,000) tons, they are extremely costly and limited as to the water depth in which they can operate.

However, when very large loads of, for example six thousand-ten thousand (6,000-10,000) tons are involved, the limitation of the derrick barge usually prohibits such a placement on an offshore jacket. The topside must then be pieced and finished offshore.

In U.S. Pat. No. 4,714,382 issued to Jon Khachaturian there is disclosed a method and apparatus for the offshore installation of multi-ton prefabricated deck packages on partially submerged jacket foundations. The Khachaturian patent uses a variable dimensional truss assembly is supported by the barge and forms a load transfer interface between the barge and the deck package. Upper and lower connections form attachments between the truss members and the deck package at upper and lower elevational positions on the deck package. The variable dimension truss includes at least one member of variable length, in the preferred embodiment being a winch powered cable that can be extended and retracted by winding and unwinding the winch. Alternate embodiments include the use of a hydraulic cylinder as an example.

An earlier patent, U.S. Pat. No. 2,598,088 issued to H. A. Wilson entitled “Offshore Platform Structure and Method of Erecting Same” discusses the placement of drilling structure with a barge wherein the legs of the drilling structure are placed while the drilling structure is supported by two barges. The Wilson device does note use truss-like lifting assemblies having variable length portions which are placed generally on opposite sides of the deck package. Rather, Wilson relates to a platform which is floated in place and the support legs are then placed under the floating platform. Thus, in the Wilson reference, an in-place underlying supporting jacket is not contemplated.

The Natvig, et al U.S. Pat. No. 3,977,346 discusses a method of placing a deck structure upon a building site such as a pier. The method includes the pre-assembly of a deck structure upon a base structure on land so that the deck structure extends outwardly over a body of water. Floating barges are provided for supporting the deck structure outwardly of the building site. The deck structure is then transferred to the supportive base structure by means of barges. The Natvig reference uses two barges which are placed on opposite sides of a platform with pedestal type fixed supports forming a load transfer member between the barges and the platform. However, the fixed pedestal of Natvig is unlike the truss-like lifting arrangement of applicant which include movable portions at least one of which can be of a variable length.

U.S. Pat. No. 4,249,618, issued to Jacques E. Lamy, discloses a method of working an underwater deposit comprising the following stages: a) constructing an positioning a platform structure, equipped before or after positioning with drilling devices and installations, b) executing drilling using these devices and installations, c) constructing and equipping, during stages a) and b), a production bridge fitted with devices and installations required for production, d) transporting the production bridge to, and positioning it on, said platform structure, and e) commencing production from deposit. The drilling bridge may remain in position on the platform structure during stages d) and e) or it may be removed to make way for the production bridge.

U.S. Pat. No. 4,744,697, issued to Anton Coppens, discloses a vessel that is provided for installing or removing a module on or from a support structure erected in a body of water. The vessel is able to suspend the module over the support structure by cranes enabling installation or removal of the module to be accomplished while the module is being suspended.

U.S. Pat. No. 5,037,241, issued to Stephen D. Vaughn et al. discloses an improved apparatus for setting a deck structure or other marine superstructure using a barge mounted cantilevered support structure. The cantilevered support structure is attached at one end of a floating vessel. The cantilevered support structure extends past the edge of the vessel and, in one embodiment, includes means for rotating parallel support members about the deck of the floating vessel permitting the cantilevered support structure to be raised and lowered while it remains substantially parallel with the top of the offshore platform enabling the superstructure to engage the top of a previously installed offshore platform in a synchronized manner. Alternatively, this superstructure may be aligned directly over the platform. A cantilevered drilling rig is then aligned over the cantilevered support structure and used to lift the deck structure or marine superstructure, permitting the vessel and cantilevered support structure to move. The drilling rig is then used to lower the marine superstructure onto the top of the previously installed offshore platform.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an improved method and apparatus for the lifting and/or placement of a multi-ton package such as a deck package, jacket, or sunken vessel. Also the present invention provides an improved method and apparatus for the removal of a multi-ton package from a marine environment, water surface, or ocean floor (i.e., sunken vessel, or from an offshore jacket.

The present invention discloses an improvement to the variable dimension truss assembly disclosed in U.S. Pat. No. 4,714,382 incorporated herein by reference.

The apparatus includes one or more barges defining a base that supports the large multi-ton load of the deck package.

In the preferred embodiment, truss-like lifting device includes a barge mounted on each side of the deck package to be lifted during operation.

In the preferred embodiment, two barges are used respectively, each having at least one truss-like lifting device on its upper deck surface. The truss preferably includes inclined and opposed booms mounted respectively on each barge, and a horizontal chord member of variable length that employs a cable wound upon a winch on each barge so that the cross-sectional dimensions of the truss can be varied by paying out or reeling in cable from the winch.

The truss forms a load transfer between each barge and the package to be lifted (e.g., deck package, or jacket) and/or placed. Upper and lower connections are formed between the lifting truss and the deck package at respective upper and lower elevational positions.

Power is provided, preferably in the form of the winch and its cable mounted on each barge for changing the length of the horizontal chord, variable length member of the truss so that elevational position of the deck package with respect to the barge can be varied such as during a lifting or lowering of the package (such as to or from a jacket foundation).

In the method of the present invention, the multi-ton deck package is first transported on a transport barge to the site where it will eventually assist in the drilling oil and/or production of a well.

In the preferred embodiment, a lifting assembly is attached to the package on generally opposite sides of the package and at upper and lower positions.

One element of the truss-like lifting assembly preferably includes a movable horizontal chord portion which has a variable length. In the preferred embodiment, the movable portion is a winch powered cable extending from each winch to a padeye connection on the package (e.g., using sheaves) to be lifted or lowered, wherein the cable can be extended or retracted between the lift barge and the deck package being lifted or lowered.

In the preferred embodiment, two lift barges support respectively first and second pluralities of truss-like lifting assemblies which in combination with the package form an overall truss arrangement. That is, the deck package itself can form a portion of the truss during the lift (typically carrying tension), and may carry both compression and tension loads.

In the preferred embodiment, the truss-like lifting assemblies have multiple booms (e.g., four) on each barge that are connected at their upper end portions to the package using a boom lifting end portion that elevates to engage a receptacle on the package. An improved connection between the booms and package is provided that uses a specially configured lifting end portion on each boom and a corresponding number receptacles on the deck package (e.g., welded thereto).

The lifting end portions support the package and can elevate it above the surface of any transport barge, so that the transport barge can be removed as a support for packages such as jackets or deck packages. This allows the package to be placed vertically above a jacket foundation and aligned with the foundation so that the deck package can be placed upon the foundation by lowering. In the case of a jacket, the transport barge can be removed so that the jacket can be lowered into the water and floated prior to installation.

The present invention allows a dimensional change in the cross-sectional configuration of the truss with respect to a vertical cross section of the truss and provides a means of raising and lowering the selected package.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:

FIG. 1 is a perspective view of the preferred embodiment of the apparatus of the present invention;

FIG. 2 is a partial perspective view of the preferred embodiment of the apparatus of the present invention;

FIG. 2A is a partial sectional elevational view of the preferred embodiment of the apparatus of the present invention;

FIG. 3 is a perspective fragmentary view of the preferred embodiment of the apparatus of the present invention illustrating the lifting end portion thereof;

FIG. 4 is a sectional view taken along lines 4—4 of FIG. 3;

FIG. 5 is a fragmentary perspective view of the preferred embodiment of the apparatus of the present invention illustrating the receptacle portion thereof;

FIG. 6 is a partial sectional elevational view of preferred embodiment of the apparatus of the present invention illustrating engagement of the boom lifting end portion and receptacle such as during lifting of a heavy deck package;

FIG. 7 is a fragmentary perspective view of the preferred embodiment of the apparatus of the present invention illustrating the bridle plate and variable length tensile member portions thereof; and

FIG. 8 is a perspective fragmentary view of the preferred embodiment of the apparatus of the present invention illustrating the boom and heel pin padeye portions thereof.

FIG. 9 is a perspective fragmentary view of the preferred embodiment of the apparatus of the present invention illustrating the movable load spreader platform portion thereof;

FIG. 10 is a sectional view taken along lines 10—10 of FIG. 9;

FIG. 11 is a fragmentary perspective view of the preferred embodiment of the apparatus of the present invention illustrating the movable load spreader platform portion thereof and its connection to the boom support connecting members;

FIG. 12 is a partial perspective exploded view of the preferred embodiment of the apparatus of the present invention illustrating the movable load spreader platform portion thereof;

FIG. 13 is a perspective view of a second embodiment of the apparatus of the present invention;

FIG. 14 is a partial, sectional, elevational view of the second embodiment of the apparatus of the present invention;

FIG. 15 is a graphical representation of sling loads for the slings 109, 110, during tow phase;

FIG. 16 is a perspective view of a alternate embodiment of the apparatus of the present invention showing the lifting apparatus positioned above a floating cargo barge;

FIG. 17 is a perspective view of the alternate embodiment of the apparatus of the present invention showing the cargo barge carrying a prefabricated jacket and with one of the sets of girder beams and the drop blocks removed for clarity;

FIG. 18 is an elevational view of a C-frame portion of the alternate embodiment of the apparatus of the present invention;

FIG. 19 is an end view of the C-frame of FIG. 18 taken along line 19—19 of FIG. 18;

FIG. 20 is a sectional view taken along lines 20—20 of FIG. 18;

FIG. 21 is a fragmentary elevational view of the alternate embodiment of the apparatus of the present invention showing the box girder portion thereof;

FIG. 22 is a fragmentary elevational view of the box girder of FIG. 21;

FIG. 23 is a sectional view taken along lines 23—23 of FIG. 22;

FIG. 24 is a fragmentary elevational view of the alternate embodiment of the apparatus of the present invention showing one side of the C-frame and its receptacle portion that receives a connection from an end of one of the lifting booms;

FIG. 25 is a sectional view taken along lines 25—25 of FIG. 23; and

FIG. 26 is a sectional view taken along lines 26—26 of FIG. 24.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 show generally the preferred embodiment of the apparatus of the present invention designated generally by the numeral 10 in FIG. 1. Lifting apparatus 10 utilizes a pair of spaced apart marine barges 11, 12 each having a respective deck 13, 14. The barges 11, 12 float on water surface 15 adjacent an underwater jacket 16 having its uppermost portion exposed in the form of a plurality of vertical columns 18 as shown in FIGS. 1 and 2.

The use of underwater jackets 16 for the purpose of supporting any number of offshore structures is well known in the art. Typically, a drilling platform, production platform, machine shop, storage facility, or like offshore structure is manufactured on land as a heavy deck package and then transported to a selected offshore marine location for placement on a jacket 16. The jacket is also usually manufactured on land as a one-piece unit, towed to a selected site on a transport vessel such as a barge, and then transferred from the barge to the marine environment. The lower end portion of the jacket engages the ocean floor or seabed with the upper vertical columns 18 extending above the water surface 15 as shown in FIGS. 1 and 2. This procedure for placing jackets so that they can support a heavy deck package 17 in a marine environment is well known in the art.

In the past, placement of such deck package 17 upon the vertical columns 18 of a jacket 16 has been accomplished using large lifting devices known as derrick barges, a huge barge having a crane thereon with a multi-ton lifting capability.

In my prior U.S. Pat. No. 4,714,382, there is provided a variable truss arrangement that uses two spaced apart barges for placing a deck package on a jacket. The Khachaturian '382 patent uses a variable dimensional truss assembly that is supported by the barge and forms a load transfer interface between the barge and the deck package. Upper and lower connections form attachments between the truss members and the deck package at upper and lower elevational positions on the deck package. The upper connection in the '382 patent is a pinned connection. The variable dimension truss of the '382 patent includes at least one member of variable length, in the preferred embodiment being a winch powered cable that can be extended and retracted by winding and unwinding the winch.

The present application relates to improvements to the subject matter of prior U.S. Pat. No. 4,714,382 which is incorporated herein by reference.

In FIG. 2, the deck package 17 is spaced above the vertical columns 18 of jacket 16. In order to place the deck package 17 on the jacket 16, the lifting apparatus 10 of the present invention slowly lowers the deck package 17 to the jacket 16 until lower end portions 19 of the deck package 17 engage and form a connection with the vertical columns 18 of the jacket 16.

Deck packages 17 are usually constructed of a plurality of welded steel pipe members including at least some of the members that are vertical. In FIGS. 1 and 2, a plurality of vertical members 20 are shown, each having a lower end portion 19 that connects with the vertical columns 18 of jacket 16.

Each of the barges 11, 12 carries a plurality of booms 21, 22. The first barge 11 has four booms 21 in FIGS. 1 and 2. Likewise, the second barge 12 has four correspondingly positioned booms 22. In FIGS. 1 and 2, the booms 21, 22 are equally spaced along the deck 13 or 14 of the corresponding barge 11 or 12 and corresponding to the position and horizontal spacing of the vertical members 20 of package 17. Further, each of the booms 27, 22 is supported upon a load spreader platform 23 or 24. The load spreader platform 23, 24 can be a combination of static load spreader platforms 23 and movable load spreader platforms 24. For example, if each barge 11, 12 has three booms, one platform 24 can be movable. If four booms, two or three platforms 24 can be movable.

The static load spreader platforms 23 are rigidly welded to and connected to the deck 13 of barge 11, or to the deck 14 of barge 12. Base plate 27 is rigidly welded to platform 23. Each load spreader platform 23, 24 has a pair of spaced apart boom heel pin padeyes 25, 26 mounted on structural base plate 27. The base plate 27 can be welded for example to its load spreader platform 23 if a “fixed” platform 23 is desired.

Each load spreader platform 23, 24 can be constructed of a plurality of perimeter beams 28 and a plurality of internal beams 29 with plate 27 mounted thereon.

The booms 21, 22 can be constructed of a pair of diagonally extending compression members 30 that form an acute angle. In FIGS. 1-2 and 8, each compression member 30 has a pair of spaced apart end caps 31 attached to each of its end portions. This is preferably a removable connection so that compression members 30 of differing lengths can be used for different lifts and the end caps 31 can be reused. Cross bar 30A spans between connecting members 35 as shown in FIG. 1, its ends being connected to members 35 using pinned connections with pins 39.

Each end cap 31 is preferably comprised of a cylindrical sleeve 32 and a plurality of plate members 33 as shown in FIG. 8. Each plate member 33 has an opening 34 that receives a pin 39. Connecting members 35 form a pinned connection with end cap 31 as shown in FIGS. 1, 2, and 8. The connecting member 35 includes a plurality of plates 36 that are parallel and a second plurality of plates 37 that are perpendicularly positioned with respect to the first plates 36 as shown in FIG. 8.

Each of the plates 37 has an opening 38 for accepting pin 39 when the connecting member 35 is attached to end cap 31 as shown in FIGS. 2 and 8. The connecting member 35 has openings 40 in each of the plates 36. This enables the plates 36 to be attached with a pinned connection to the heel pin padeyes 25, 26 as shown in FIGS. 2 and 8.

A variable length tensile member 42 extends between heel pin padeyes 25, 26 and a vertical member 20 of package 17. As shown in FIG. 1, this centers a variable length tensile member 42 and a boom 21 or 22 on each vertical member 20. As shown in FIG. 1, there are four spaced apart vertical members 20, each having a respective boom 21 or 22 connected thereto and each having a variable length tensile member 42 extending from the barge 11 or 12 to the vertical member 20.

Each variable length tensile member 42 includes a cable 43 wound upon a pair of sheaves 44, 45 as shown in FIGS. 2, 2A, and 7. The sheave 45 is constructed of a pair of plates 46 that are spaced apart so that padeye 50 fits in between the plates 46. A pinned connection can be formed between padeye 50 and plates 46 of sheave 44 using pin 52 that is inserted through the openings 47 of plate 46 and the opening 51 of padeye 50.

The padeye 50 is structurally connected (welded, for example) to bridle plate 48. The bridle plate 48 includes a structural plate body 49 having a pair of plates 53 and 54 at its end portions respectively as shown in FIG. 7. Each of the plates 53, 54 has openings 55 through which pin 41 can be inserted when the plates 53 or 54 are connected to respective heel pin padeyes 25, 26, as shown in FIGS. 2 and 7 e.g., with a load cell 89.

Each boom 21, 22 provides a lifting end portion 56 that is shown particularly in FIGS. 2 and 3-6. The lifting end portion 56 of each boom 21, 22 forms a connection with a receptacle 70 that is mounted on vertical member 20 as shown in FIGS. 1, 2, 5, and 6. The lifting end portion 56 is constructed of a plurality of spaced apart parallel plates 57. Each plate 57 has an opening 58. Gaps 59, 60 are provided for receiving plates 33 of an end cap 31. This connection can be seen in FIGS. 2 and 6. The lifting end portion 56 provides a pair of inner plates 61 that can be parallel to one another and a pair of outer plates 62 that can form an acute angle.

Roller 63 is positioned in openings formed through the plates 61 as shown in FIGS. 3 and 4. Each roller 63 is preferably of an hour glass shape, having a narrow or neck portion 64 and a pair of cylindrically-shaped end portions 65. Arrow 66 in FIG. 4 illustrates that the roller 63 can move side to side for adjustment purposes when the booms 21 and 22 are connected to the receptacle 70 and thus to the deck package 17. In order that roller 63 be allowed to move from side-to-side, there are provided gaps 68 on each side of the roller 63 as shown in FIG. 4. Stop plates 67 are shaped to limit movement of the roller 63 as it moves from one side to the other as shown by arrow 66.

Lifting end portion 56 can be connected to the selected boom 21 or 22 with pin connections 69 as shown in FIG. 6. The openings 58 in plates 57 receive a pin therethrough, that pin also passing through the openings 34 in plates 33 of end cap 31.

Receptacle 70 is shown more particularly in FIGS. 2, 5, and 6. Receptacle 70 includes a curved plate 71 that is attached to vertical member 20 of deck package 17, being structurally affixed thereto by welding, for example.

Receptacle 70 is formed of a plurality of flat elates including a center plate 72 and a pair of smaller side slates 73, 74, as shown in FIG. 5. Recess 75 receives roller 63 upon engagement of lifting end portion 56 and receptacle 70 as shown in FIG. 6. The neck 64 portion of roller 63 is of a reduced diameter and is shaped to engage inclined edge 76 of plate 72, then travel upwardly along inclined edge 76 until the neck 64 of roller 63 fully nests in recess 75 of receptacle 70. This fully engaged position of lifting end portion 56 and receptacle 70 is shown in FIG. 2.

The receptacle 70 is formed of a pair of vertical sections 77 and 78, and a transversely extending section 79. The section 79 can have a flat upper surface that receives reinforcing plate 80, that can be a horizontally extending plate. In FIG. 6, further reinforcement of the attachment of receptacle 70 to deck package 17 is seen. In FIG. 6, the horizontal plate 80 is rigidly affixed to the bottom of a horizontal beam 81 by welding, for example. This enables the loads transmitted from lifting end portion 56 to receptacle 70 to be transferred to the deck package 17 at vertical member 20 and at horizontal beam 81.

In FIGS. 2 and 6, arrows 82 illustrate the upward movement of lifting end portion 56 that is used to nests roller 63 in recess 75 of receptacle 70. In FIG. 2, arrow 83 illustrates the upward and downward movement of lifting end portion 56 of booms 21 and 22 to either engage or disengage the boom 21 or 22 from the deck package 17.

In order to lower the deck package 17, the cable 43 is unwound using a winch that is carried on the surface of deck 13 or 14 of barge 11 or 12. This lengthens the distance between heel pin padeyes 25, 26 and the deck package 17. By lengthening the distance between the padeyes 25 and 26 of the respective barges 11 and 12, the variable length tensile member 42 is elongated so that the booms 21 and 22 rotate downwardly about their heel pin padeyes 25, 26 creating a smaller and smaller angle between the compression members 30 and the barge decks 13, 14.

This procedure is reversed in order to lift a deck package 17 upwardly with respect to water surface 15 and jacket 16. in such a lifting situation, the winch mounted on the deck 13 or 14 of the barges 11 and 12 winds the cable 43 to shorten the distance between sheaves 44, 45. This likewise shortens the distance between the heel pin padeyes 25 and 26 on barge 11 with respect to the heel pin padeyes 25 and 26 on barge 12. The effect is to elevate the lifting end portion 56 and to increase the angle between the compression members 30 and the barge decks 13, 14.

In such a lifting situation, tension member 85 can be used in between opposed vertical members 20 as shown in FIGS. 1 and 2. Padeyes 87, 88 can be welded, for example, to vertical member 20 for forming an attachment between tension member 85 and the vertical column 20. Likewise, a tension member 86 can be placed in between padeye 87 and sheave 45 as shown in FIG. 2. Thus, a continuous tensile member is formed in between the heel pin padeyes 25, 26 of barge 11 for each boom 21, and the corresponding heel pin padeyes 25, 26 on barge 12 for each of its booms 22.

During a lifting of a package 17, hook-up is first accomplished. The booms 21, 22 are positioned so that the lifting end portion 56 of each boom 21, 22 is positioned below the corresponding receptacle 70 on package 17.

An operator or operators then begin hook-up by attaching the cables 43 and sheaves 44, 45 to the corresponding vertical members 20, configured as shown in FIGS. 1, 2, and 2A. The winch W1 then shortens cable 43 pulling barges 11, 12 toward package 17. In such a situation, the lifting end portion 56 will engage vertical member 20 at a position below receptacle 70. The plates 62 of lifting end portion 56 will engage vertical member 20 and end portion 56 then slides upwardly on the vertical member 20 as cable 43 is shortened until end portion 56 reaches receptacle 70. Continued shortening of the cable 43 increases the angle of inclination of each boom 21, 22 relative to the deck 13, 14 respectively of barges 11, 12 until lifting end portion 56 registers completely in recess 75 of receptacle 70. Then, continued shortening of the cable 43 associated with each boom 21, 22 effects a lifting of the padeyes 17 as the boom 21, 22 angle of inclination relative to the barge 11, 12 deck 13, 14 further increases. The booms 21, 22 are simultaneously elevated and inclined continuously so that each of the booms 21, 22 shares a substantially equal part of the load. This can be monitored using load cell link 89 that can be used to monitor the tension between bridle plates 48 and the pinned connection that joins padeyes 25, 26 and connecting members 35.

A second winch W2 can be rigged with a wound line or cable for pivoting each boom 21, 22 relative to the deck 13, 14 of barge 11, 12 respectively (see FIG. 2A) such as may be required during an initial positioning of the booms 21, 22 before a hook-up.

In FIGS. 9-12, there can be seen more particularly the construction of movable load spreader platform 24. The plate 27A in FIG. 9 is a support plate that sits upon the various perimeter beams 28 and internal beams 29 of movable load spreader platform 24. However in FIGS. 9-12, elongated slots 90 are provided for receiving bolted connections B as shown in FIG. 11. Each of the slots receives the upper threaded end portion of a bolt 91 as shown in FIGS. 9-12. In this fashion, the plate 27A can slide as shown by the arrow 92 in FIG. 11. This enables the boom 21 or 22 that is a affixed to connecting members 35 some adjustment in its position with respect to the supporting barge 11 or 12. This is important because it enables minor defects in construction in either of the deck package 17 or either of the barges 11, 12 or of the various load spreader platforms 23, 24 to be compensated for during attachment of the booms 21, 22 to the deck package 17 to be lifted. The threaded upper end 93 of each bolt 91 can then receive a nut 94 to complete the bolted connection B. It should be understood that during use, it is not necessary that the bolted connections be torqued and/or tightened. This is because the compression loads transmitted from the boom 21 or 22 to the plate 27A and then to the load spreader platform is sufficient to hold the plate 27A in position not withstanding that the nuts 94 are fully tightened. In fact, during initial connection of the booms 21, 22 to the deck package 17, some adjustability of plate 27A with respect to beams 28, 29 is desirable.

FIGS. 13 and 14 show a second embodiment of the apparatus of the present invention designated generally by the numeral 100 in FIGS. 13 and 14. In the embodiment of FIGS. 13 and 14, the variable length tensile member 42 is replaced with one or more fixed length members 109, 110 that span respectively from barges 11, 12 to a work structure designated by the numeral 101. When the variable length tensile member 42 of the preferred embodiment of FIGS. 1-12 is replaced with the fixed length member 109, 110 of FIGS. 13 and 14, a catamaran structure 100 is provided that can be used as a work platform for servicing offshore oil and gas platforms, production facilities, well heads and the like.

The catamaran structure 100 thus includes the two barges 11, 12, the work platform 10l, and the booms 21, 22 and fixed members 108, 109, 110, to rigidify the entire structure so that the only movement between the barges 11 and 12 relative to the work platform 101 is rotational or pivotal movement as shown by the arrows 111, 112, in FIG. 14. The same booms 21, 22, and barges 11, 12, are used as with the preferred embodiment to form an initial connection between each boom 21, 22, and the work platform 101 using for example, the same type of connections shown in FIG. 6 with the preferred embodiment. The lift uses receptacle 70, lifting end portion 56, end caps 31, and compression members 30. This enables the length of the booms 21, 22 to be varied, depending on the configuration desired. For example, the present invention enables barges 11 and 12 to be used with work platforms 101 of different sizes. By changing the length of the compression members 30, different work platforms 101 can be accommodated. Further, the angle between each boom 21, 22, and the water surface 15 can be varied as well, using different length compression members 30, and different length members 109, 110.

The platform 101 can be similar in configuration to the deck package 17 shown in the preferred embodiment of FIGS. 1-12. The work platform 101 can be comprised for example of a plurality of vertical columns 104, 105, and a plurality of spaced apart decks including eg. lower deck 102 and upper deck 103. Openings 107, 108 can be provided through decks 102, 103 respectively, so that lift lines 113, 114 can pass through openings 104, 115, as shown in FIG. 14. Such lift lines 113, 114, can be powered using winches 115, 116, respectively. This enables the work platform 101 to be elevated and perform many of the functions of jack-up type rigs, for example. Further, the present invention enables the apparatus 100 of the present invention to be used for lifting submerged structures such as offshore jackets 16 upwardly during salvage operations.

The use of fixed members 109, 110 in place of the variable length tensile members 42 of the preferred embodiment, provides a very stable structure 100 that is of a fixed geometry for extended use such as during transport to and from offshore locations, and functioning as a work platform or a work boat of catamaran type to perform many offshore maintenance and salvage jobs.

FIG. 15 shows sling loads during tow phase. The sling load (short tons) is plotted against elapsed time. During such an actual tow, the slings 109, 110 experienced little variation in sling load due to the overall stability of apparatus 100.

FIGS. 16-26 show an alternate embodiment of the apparatus of the present invention designated generally by the numeral 120 is FIGS. 16-17.

Lifting apparatus 120 includes a pair of spaced apart barges 11, 12 each having an upper deck 13, 14. These barge members 12, 13 can float on a water surface 15 during use such as during installation of an offshore marine jacket, platform or deck package, designated generally by the numeral 16 in FIGS. 17 and 18.

The jacket or package 16 to be lifted can be supported upon a cargo barge designated by the numeral 121 having an upper deck 122. As with the preferred embodiment, the barges 11, 12 can be provided with a plurality of lifting booms. The barge 11 has a pair of booms 21. The barge 12 has a pair of booms 22. Each of the booms 21, 22 can be constructed in accordance with FIGS. 2, 2A and 3-12. Each boom 21, 22 thus provides and end portion having a lifting end portion 56 such as is shown in FIGS. 3-6 that engages a receptacle 70 mounted on each C-frame 123 as will be described more fully hereinafter.

In FIGS. 16-26, the lifting apparatus 120 includes the booms 21, 22 supported upon barges 11, 12. The booms 21, 22 support two spaced apart C-frames 123. Upon these spaced apart C-frames are mounted four girders 124 as shown. The overhead hoists can be wheeled to ride upon rails 143 on the top of girders 124 (see FIGS. 17 and 24).

Overhead hosts 125 are mounted upon pairs of girders 124 as shown in FIG. 17. Each of the girders 124 attaches to a C-frame 123 with an articulating connection at fitting 126. This articulating connection is formed by a pinned connection that extends through fitting 126 and through an end of each girder 124 at opening 127, the horizontal pin 137 being carried by fitting 126 that can be in the form of a gusseted block with openings to receive the horizontal pins. The fitting 126 provides an articulating connection. Fitting 126 in FIG. 24 is shown as comprising horizontal plate 138 and a plurality of four vertical plates 139, each having an opening 140 to receive horizontal pin 137. Vertical pin 141 extends downwardly from horizontal plate 138 (see FIGS. 17, 24 and 25) to enter vertical socket 142 in C-frame 123. Fitting 126 is thus pinned to the top of a C-frame 123. Fitting 126 and pins 137, 141 provide an articulating interface joining each of the girders 124 at its end portion to a C-frame 123.

Openings 128 are provided at the bottom of each C-frame as shown in FIGS. 16-17 and 24. The openings 128 are rigged to cables that form a harness as shown in FIGS. 16-17. This harness is comprised of gate sling 129, starboard stabilizing sling 130, starboard winch sling 131, port stabilizing sling 132, port winch sling 133 and vertical slings 134, 135. Gate sling 129 can be disconnected in order to move a barge 122 with a jacket 16 (or other object to be lifted) under C-frames 23.

The winch slings 131, 133 can be tightened to raise the C-frames 123 relative to barges 11, 12. This enables the harness that is comprised of the slings 129, 130 and 132 to be rigged. The operator of apparatus 120 then uses the winch slings 131, 133 to lower the C-frames 132 to apply tension to the harness that is comprised of the lines 129, 130, 131, 132, 133. This combination of tension on the lines 129-133 provides stabilizing during transport and during use. The port stabilizing sling 132 and starboard stabilizing sling 130 are anchored to the base of the respective booms 22, 21 at the boom heel pin padeye 25 or 26 using a bridle plate 49 and connecting member 35 (see FIGS. 2, 2A, 7, 11). Similarly, each port winch sling 133 and starboard winch sling 130 are anchored to the base of the respective booms 22, 21 the boom heel pin padeye 25 or 26.

The flexibility of this system 120 of the present invention allows it to take a greater sea state at a lighter weight. The present invention thus provides and improved fixed overhead offshore crane apparatus 120 for lifting and placing jackets 16 or other like structures and/or for reclaiming such jackets 16 or other structures from the sea bed for from a marine environment.

The following table lists the parts numbers and parts descriptions as used herein and in the drawings attached hereto.

PARTS LIST Part Number Description  10 lifting apparatus  11 barge  12 barge  13 deck  14 deck  15 water surface  16 jacket  17 deck package  18 vertical column  19 lower end portion  20 vertical member  21 boom  22 boom  23 static load spreader platform  24 movable load spreader platform  25 boom heel pin padeye  26 boom heel pin padeye  27 floating heel pin base plate  28 perimeter beam  29 internal beam  30 compression member  30A cross bar  31 end cap  32 cylindrical sleeve  33 plate  34 opening  35 connecting member  36 plate  37 plate  38 opening  39 pin  40 opening  41 pin  42 variable length tensile member  43 cable  44 sheave  45 sheave  46 plate  47 opening  48 bridle plate  49 body  50 padeye  51 opening  52 pin  53 plate  54 plate  55 opening  56 lifting end portion  57 plate  58 opening  59 gap  60 gap  61 inner plate  62 outer plate  63 roller (hourglass shape)  64 neck  65 cylindrical end  66 arrow  67 stop plate  68 gap  69 pinned connection  70 receptacle  71 curved plate  72 plate  73 plate  74 plate  75 recess  76 inclined surface  77 vertical section  78 vertical section  79 transverse section  80 horizontal plate  81 horizontal beam  82 arrow  83 arrow  84 arrow  85 tension member  86 tension member  87 padeye  88 padeye  89 load cell link  90 slot  91 bolt  92 arrow  93 threaded portion  94 nut B bolted connection W1 winch W2 winch 100 catamaran work platform apparatus 101 work platform 102 lower deck 103 upper deck 104 opening 105 opening 106 vertical column 107 vertical column 108 transverse beam 109 fixed length member 110 fixed length member 111 arrow 112 arrow 113 lift line 114 lift line 115 winch 116 winch 120 lifting apparatus 121 barge 122 barge deck 123 C-frame 123H horizontal section 123V vertical section 124 girder 125 overhead hoist 126 fitting 127 opening 128 opening 129 gate sling 130 starboard stabilizing sling 131 starboard winch sling 132 port stabilizing sling 133 port winch sling 134 vertical sling 135 vertical sling 136 pin 137 horizontal pin 138 horizontal plate 139 vertical plate 140 opening 141 vertical pin 142 vertical socket 143 rail

Because many varying and different embodiments may be made within the scope of the inventive concept herein taught, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense. 

What is claimed as invention is:
 1. A catamaran work barge apparatus for lifting a large multi-ton package, comprising: a) a pair of barges, each defining a base, the barges being configured and sized to support the large multi-ton package; b) a plurality of lift booms supported respectively by the barges and positioned about the periphery of the package for forming a load transfer between the barges and the package to be lifted; c) each lift boom having a lower end portion attached to a barge and an upper free end portion; d) a structural frame having a receptacle thereon that receives the boom lifting free end portion; and f) an adjustable length lifting line depending from the frame for lifting the package when the package is positioned generally between the barges and below the frame.
 2. The lifting apparatus of claim 1 wherein the lifting line is a powered lifting line powered by a winch supported by the frame.
 3. The lifting apparatus of claim 2 wherein there are at least two lift booms on each barge.
 4. The lifting apparatus of claim 3 wherein the barges have horizontal load spreader surfaces spaced generally on opposite sides of the package being lifted, the lift booms being mounted upon said load spreader surfaces.
 5. The lifting apparatus of claim 2 wherein the lift booms are each pinned to a different one of the barges and are angularly disposed with respect to each other during use.
 6. The lifting apparatus of claim 1 wherein end caps form a detachable interface between the booms and the frame.
 7. The lifting apparatus of claim 1 wherein the structural frame includes a pair of frame members, each frame member being supported by a pair of said lift booms.
 8. The lifting apparatus of claim 7 further comprising a girder beam that spans between the frame members.
 9. The lifting apparatus of claim 8 wherein there are at least a pair of girder beams that extend between said frame members.
 10. The lifting apparatus of claim 8 further comprising a drop block lifting line assembly supported by the girder.
 11. The lifting apparatus of claim 9 further comprising a drop block lifting line assembly supported by the girders.
 12. The lifting apparatus of claim 1 further comprising a drop block lifting line assembly supported by the frame that comprises said lifting line.
 13. The lifting apparatus of claim 1 wherein there are a plurality of said lifting lines depending from said frame.
 14. The lifting apparatus of claim 13 further comprising a plurality of drop block lifting line assemblies supported by the frame that each comprise a lifting line.
 15. The lifting apparatus of claim 1 further comprising a drop block lifting line assembly supported by the frame that comprises said lifting line.
 16. The apparatus of claim 7 wherein the flame is comprised in part of a horizontal portion that extends between upper end portions of lift booms on different of the barges.
 17. A method for lifting a multi-ton structure in an offshore marine environment, comprising the steps of: a) transporting a work platform to a desired site with a pair of barges that are positioned in spaced apart and generally parallel positions relative to one another, the barges providing a lifting assembly that support the work platform; b) attaching a lifting assembly to the multi-ton structure at multiple positions including positions that are at least on generally opposite sides of the multi-ton structure, and at upper and lower positions on the multi-ton structure respectively; c) the lifting assembly including a plurality of diagonally extending, inclined booms carried by the barges, the upper end of the booms supporting the work platform, the lifting assembly including a tensile cable member joining the barges to the combination of work platform and the multi-ton structure to be lifted; d) wherein in step “a” the booms are each connected by at least one lifting end portion to a receptacle on the work platform; and e) lifting the multi-ton structure with lifting lines depending from the work platform.
 18. The method of claim 17, wherein the boom end includes a roller that fits the receptacle.
 19. The method of claims 17, wherein there are two opposed lift barges that are floating barges.
 20. The method of claim 17, wherein one portion of the lifting assembly includes a plurality of compression carrying diagonally extending lift booms, each with opposing end portions and a plurality of end caps that removably attach to the end portions of the booms, at least some of the end caps being supported by the barges.
 21. The method of claim 20, wherein the lifting assembly includes a plurality of non-extensible diagonally extending lift booms, each removably connecting at one of its ends to one or more end caps at least some of the end caps being supported by a barge.
 22. A method for lifting a multi-ton structure in an offshore marine environment, comprising the steps of: a) providing a work platform; b) attaching a lifting assembly to the work platform; c) wherein the lifting assembly includes opposed floating barges having diagonally extending lifting booms thereon connected at their upper ends with a lifting end portion to the work platform; d) structurally supporting each of the lifting booms at the lower end portion thereof with one of the barges, each boom being pivotally attached to its barge; e) wherein the work platform has receptacles thereon, each receptacle with a downwardly oriented recess that receives the lifting end portion of a boom as the boom inclination increases relative to the deck of the barge; f) supporting the work platform with horizontal chords extending between the barges and platform; g) providing drop blocks with lifting lines on the platform for selectively raising or lowering the structure; h) connecting the drop block lifting lines to the structure; and i) moving the structure to a desired elevational position with the lifting lines.
 23. A lifting apparatus for lifting a multi-ton structure in an offshore marine environment, comprising the steps of: a) a work platform; b) a pair of barges that are positioned in spaced apart positions relative to one another, the barges providing a lifting assembly that supports the work platform; c) the lifting assembly including a plurality of diagonally extending, inclined booms carried by the barges, the upper ends of the booms supporting the work platform; d) powered lifting lines depending from the work platform that enable the multi-ton structure to be lifted.
 24. The lifting apparatus of claim 33 wherein there at least two lifting booms on each barge.
 25. The lifting apparatus of claim 20 wherein each boom is pivotally attached to one of said barges.
 26. The lifting apparatus of claim 23 wherein the barges have horizontal load spreader surfaces spaced generally on opposite sides of the package being lifted, the booms being mounted upon said load spreader surfaces.
 27. The lifting apparatus of claim 23 wherein the booms are each pinned to a different one of the barges and at least some of the booms are angularly disposed with respect to each other during use.
 28. The lifting apparatus of claim 23 wherein end caps from a detachable interface between the booms and a barge.
 29. The lifting apparatus of claim 23 wherein there are a plurality of said lifting lined depending from said work platform.
 30. The lifting apparatus of claim 23 further comprising a drop block lifting line assembly supported by the work platform that comprises said lifting line.
 31. The lifting apparatus of claim 23 wherein the work platform is comprised of a horizontal portion that extends generally between upper end portions of booms on different of the barges.
 32. The lifting apparatus of claim 23 wherein the lifting line is a winch cable wound upon a powered winch.
 33. The lifting apparatus of claim 23 wherein the lifting line is powered lifting line, powered by a winch supported by the work platform.
 34. The lifting apparatus of claim 23 wherein the work platform includes a pair of frame members, each frame member being supported by a pair of said lift booms.
 35. The lifting apparatus of claim 34 further comprising a girder beam that spans between the frame members.
 36. The lifting apparatus of claim 34 wherein there are at least a pair of girder beams that extend between said frame members.
 37. The lifting apparatus of claim 35 further comprising a drop block lifting line assembly supported by the girder.
 38. The lifting apparatus of claim 36 further comprising a drop block lifting line assembly supported by the girder.
 39. The lifting apparatus of claim 23 further comprising a drop block lifting line assembly supported by the work platform that comprises said lifting line.
 40. The lifting apparatus of claim 24 wherein each boom has an end portion that includes a roller, and the work platform as receptacles that enable connection to the booms at the rollers.
 41. The lifting apparatus of claim 24 wherein there are two opposed barged that are floating barges.
 42. The lifting apparatus of claim 24 wherein the lifting assembly includes a plurality of compression carrying diagonally extending lift booms, each with opposing end portions and a plurality of end caps that removably attach to the end portions of the booms, at least some of the end caps being supported by the barges.
 43. The lifting apparatus of claim 24 wherein the lifting assembly includes a plurality of non-extensible diagonally extending lift booms, each removably connecting at one of its ends to one or more end caps, at least some of the end caps being supported by a barge.
 44. A method for lifting a multi-ton structure in an offshore marine environment, comprising the steps of: a) providing a work platform; b) attaching a lifting assembly to the work platform, wherein the lifting assembly includes opposed barges having lifting booms thereon that are connected at their respective upper ends with a lifting end portion to the work platform; c) structurally supporting each of the lifting booms at the lower end portion thereof with one of the barges, each boom being movably attached to its barges; d) providing drop blocks with lifting lines on the work platform for selectively raising or lowering the structure; e) connecting the drop block lifting lines to the structure; and f) moving the structure to a desired elevational position with the lifting lines. 